Anti-varnish lubricating composition



. mation.

ANTI-VARNISH LUBRICATING COMPOSITION Roderick S. Spindt, Allison Park, and Donald R. Stevens,

Wilkinsburg, Pa., assignors to Gulf Research and Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed Nov. 29, 1955, Ser. No. 549,886

6 Claims. (Cl. 25242.7)

This invention relates to a method of opera-ting an internal combustion engine under conditions such that varnish deposition is minimized and more particularly to a lubricating composition having improved antivarnish characteristics.

The deposition of gum, varnish and sludge on the interior surfaces of automotive, aviation and diesel engines and the accumulation of these deposits in the oil used to lubricate such engines deleteriously affects their operation and in many instances gives rise to engine failure. For many years the accumulation of sludge in the lubricating oil and the deposition of gum and varnish on engine parts was considered to be the result of using an inferior lubricating oil. While the lubricating oil may be a contributing factor in the formation of gum, varnish and sludge, it is not the sole factor. Other factors which contribute to engine deposits include engine design, engine operation conditions, engine maintenance and the type of fuel employed in the engine.

The automotive and petroleum industries have improved engine design, lubricating oil and fuel to such an extent that engine deposits resulting from these variables have been minimized. Other variables, including mode of operation and maintenance are not readily controlled to give optimum engine performance. Even if the operator of the engine uses extreme care in its operation and maintenance there are certain unavoidable service conditions which favor sludge and varnish for- For example, engine deposits can be formed at high-temperature operation normally encountered when driving for an extended period of time at high speeds. On the other hand, engine deposits can be formed at low-temperature operation normally associated with intermittent use of the engine. Engine deposits formed as a result of intermittent operation of the engine at low temperatures are more prevalent because these are the conditions under which a high percentage of the automotive engines are being operated.

We do not wish to be limited to any theory concerning the formation of varnish at low temperatures. However, we believe that varnish formation at low temperatures is due primarily to the lubricating oil becoming diluted with unburned fuel and to the reaction product of nitrogen oxides with fuel residues. Contamination of the lubricating oil with unburned fuel and nitrogen oxide reaction products is believed to result from leakage of combustion chamber gases past the piston rings into the crankcase. These gases are commonly referred to as blow-by gases. Irrespective of the cause of varnish deposition, this invention is directed to a lubricating composition for reducing varnish deposition associated with low-temperature operation and to a method of operating an internal combustion engine whereby varnish deposition is materially reduced.

We have found that the deposition of engine varnish associated with low-temperature operation can be substantially reduced if, during the operation of the engine at said low temperature, the crankcase of theengine nited States Patent 2,966,462 Patented .Dec. .27, 1960 ice contains a mineral lubricating oil and a nitrogen compound selected from the group consisting of hydrazine, mono-alkyl and di-alkyl substituted hydrazines, salts of hydrazine and salts of mono-alkyl and di-alkyl substituted hydrazines. For example, we have found that an engine operated under conditions normally tending to favor the deposition of varnish on the pistons of the engine, can be operated with substantial reduction in varnish deposition if the crankcase contains a lubricating composition comprising a major amount of a mineral lubricating oil and a minor amount of a compound selected from the group consisting of hydrazine, monoalkyl and di-alkyl substituted hydrazines, salts of hydrazine, and salts of mono-alkyl and di-alkyl substituted hydrazines.

We prefer to employ anhydrous hydrazine which can be obtainedby any known method. For example, it can be obtained by refluxing to percent hydrazine hydrate with a dehydrating agent such as potassium hydroxide, sodium hydroxide, calcium oxide, etc., followed by distillation in an inert atmosphere or under vacuum. Anhydrous hydrazine is available commercially. Its preparation constitutes no part of this invention.

The mono-alkyl and di-alkyl substituted hydrazines particularly suitable for the purpose of the invention are those hydrazines substituted with an alkyl group containing 1 to 18 carbon atoms. Examples of such compounds are methylhydrazine, dimethylhydrazine, ethylhydrazine, diethylhydrazine, propylhydrazine, dipropylhydrazine, butylhydrazine, dibutylhydrazine, and the like.

The salts of hydrazine, mono-alkyl and di-alkyl substituted hydrazines which we can employ are the organic salts prepared by reacting hydrazine or its alkyl substituted derivative With a fatty acid, a naphthenic acid, a sulfonic acid, a di-alkyl dithiophosphoric acid, a phenol or with a thiophenol.

The naphthenic acids which we can employ in making the hydrazine and the alkyl hydrazine salts are found in crude oils, primarily in naphthenic-base and asphaltbase crudes. These acids are cyclic compounds consisting predominantly of cyclohexyl or cyclopentyl acetic acids or homologs of them. Of the naphthenic acids which are available commercially we prefer the C to C naphthenic acids. However, higher molecular weight acids, i.e., those containing more than 12 carbon atoms and including those having double naphthenic rings can be used.

The sulfonic acids which we can employ in making the hydrazine and the alkyl hydrazine salts are the organic sulfonic acids having the general formula RSO H where R is alkyl, aryl, alkaryl and aralkyl. Examples of some such acids are hexane sulfonic acid, benzene sulfonic acid, p-toluene sulfonic acid, Z-naphthalene sulfonic acid, 1,6-naphthalene disulfonic acid, and the like. Because of the oil solubility imparted to the compounds by the longer chain hydrocarbons, we prefer to employ the organic s'ufonic acids containing at least 6 carbon atoms in the organic radical attached to the aromatic nucleus. A preferred group of compounds are the alkyl and alkaryl sulfonic acids wherein the alkyl group contains about 6 to about 18 carbon atoms. In any event, the alkyl group is of sufficient length to impart oil solubility to the resulting salt of hydrazine or alkyl hydrazine.

' The dialkyl dithiophosphoric acids which can be used in accordance with our invention are advantageously those wherein the alkyl group contains from 6 to 18 carbon atoms. Examples of suitable compounds of this type are dicyclohexyl dithiophosphoric acid, di-(Z-ethyl hexyl)-' dithiophosphoric acid, didecyl dithiophosphoric acid, octyldecyl dithiophosphoric acid, and the like.

The fatty acids particularly suitable in the. preparas tion of the hydrazine and the alkyl hydrazine salts are those having 8 to 18 carbon atoms. Branched chain or cyclic as well as straight chain acids can be employed. Included among the preferred fatty acids are ethylhexanoic, caprylic, capric, lauric, myristic, palmitic, stearic, oleic and linoleic.

By the term phenol as used in connection with the preparation of the salts of hydrazine and alkyl hydrazine it should be understood that we intend to include phenol itself and its homologs including monoand polyalkyl substituted phenols such as ortho-cresol, meta-cresol, para-cresol, or mixtures of these such as are found in commercial cresylic acids, xylenols, ethyl phenols, propyl phenols, nonyl phenols, ethyl cresols, propyl cresols, butyl cresols, and the like. The homologs of phenol which we can use are advantageously those alkyl substituted phenols having from 1 to 18 carbon atoms in the alkyl group.

As established hereinabove, in preparing the salts we can employ hydrazine or its homologs including mono alkyl and di-alkyl substituted hydrazines such as methylhydrazine, dimethylhydrazine, methylethylhydrazine, ethylhydrazines, propylhydrazines, and the like. When an alkyl hydrazine is used in the preparation of a salt, we prefer to employ those compounds wherein the alkyl group contains from 1 to 18 carbon atoms. While the alkyl substituents of the alkyl hydrazine and the alkyl substituted fatty acid or the alkyl substituted phenol can contain the same number of carbon atoms, it should be understood that these alkyl substituents can be different. Thus, for example, dimethylhydrazine can be reacted with 2-ethylhexanoic acid to produce dimethylhydrazinium 2'ethylhexanoate; dimethylhydrazine can be reacted with nonylphenol to produce dimethylhydrazinium nonylphenate; propylhydrazine can be reacted with oleic acid to produce propylhydrazinium oleate; and methyl-ethylhydrazine can be reacted with Z-ethylhexanoic acid to produce methylethyl hydrazinium 2-ethylhexanoate.

Examples of suitable salts of hydrazine which can be used in the composition of our invention are hydrazinium caprylates, caprates, laurates, oleates, naphthenates, sulfonates, dialkyldithiophosphates, phenates and thiophenates; methylhydrazinium caprylates, caprates, laurates, oleates, naphthenates, sulfonates, dialkyldithiophosphates, phenates and thiophenates; dimethylhydrazinium caprylates, caprates, laurates, oleates, naphthenates, sulfonates, dialkyldithiophosphates, phenates and thiophenates; and the like. i

The hydrazinium salts are readily prepared by reacting equi-molar proportions of the hydrazine or alkyl hydrazine and acid, hydrazine or alkyl hydrazine and phenol, and hydrazine or alkyl hydrazine and thiophenol at room temperature and atmospheric pressure.

Hydrazine, alkyl hydrazine or their salts can be added to the oil in amounts between about 1 and about 10 percent based on the weight of the oil. When operating an engine with a thermally crackedgasoline and a highly 17efined parafiinic mineral lubricating oil, we have obtained good results with about one percent by weight of anhydrous hydrazine. The optimum amount of hydrazine, alkyl hydrazine or their salts may vary depending upon the particular engine. in which the oil is used, the lubricate ing oil, the fuel on which the engine is operated, the operating onditi ns. and he pe a o he hydra ne salts r use the op mum amou m y be fi r ro the p imum mo n f hy raz ne ewi e, the p mum am f alky yd azine. m y e d ffer n fro he on timum amount of alkyl hydrazine salt. In any event, the amount, of hydrazine, alky hy ra s of h i or alkyl hydrazine salt, used in suflicient to materailly reduce the amount of varnish which would, otherwise be formed under identical circumstances if hydrazine, alkyl hydrazine or their salts were not present.

In some instances, as when using hydrazine or certain salts of hydrazine, it may be desirable to. employ one. or

more solvating agents to eifect more rapid and more complete dispersion of the hydrazine or its salt in the oil. Suitable solvating agents include oleyl alcohol, oleic acid, phenol, and the like. In instances where the use of a solvating agent is desired ordinarily only a relatively small amount of such agent may be necessary. However, as much as about 50 percent by weight based on the weight of the hydrazine or its salt can be used.

The mineral lubricating oil to which the hydrazine or its salt is added can be any oil having a viscosity within the range of common lubricating oils. The oil can be either refined or semi-refined paraflnic, naphthenic or asphaltic base oil having a viscosity of about 50 to about 4000 SUS at 100 F. If desired, a blend of oils of suitable viscosity can be employed instead of a single oil by means of which any desired viscosity within the range of 50 to 4000 SUS at 100 F. can be secured. The oil content of the compositions prepared according to this invention can comprise about to about 99 percent or more by weight of the total composition. The particular oil as well as the exact amount of oil employed depends upon the characteristics desired in the final composition.

The lubricating composition of our invention can contain minor amounts of addition agents other than hydra-. zine, alkyl hydrazine or their salts. Thus, for example, it is particularly advantageous in many instances to add an anti-foam agent to the lubricating composition. Other addition agents normally added to lubricating oils for a specific purpose, such as an anti-oxidant, pour point depressant, corrosion inhibitor, viscosity index improver, oiliness and extreme pressure agent, and the like, can be employed without adversely affecting the improved antivarnish characteristics derived by the composition of this invention.

The fuel employed in operating the engine can be a straight-run gasoline, a cracked gasoline, or blends thereof. The fuel can also contain components obtained from processes other than cracking, such as components obtained from alkylation, isomerization, hydrogenation, polymerization, hydrodesulfurization, hydroforrning platforming, or combinations of two or more of such processes, as well as synthetic gasoline obtained from the Fischer-Tropsch and related processes. A straight-run gasoline is usually cleaner burning than a cracked gasoline, and for this reason the amount of hydrazine, alkyl hydrazine or their salt required when an engine is op: erated with a straight-run gasoline may be less than the amount used when a cracked gasoline is employed.

Typical properties of thermally and catalytically cracked gasolines of the type used in making the tests reported herein as follows:

Thermally Catalyt- Craeked ically Cracked Gravity, API 60.0 55. 7 Sulfur, L, Percent" 0.041 Copper Dish Gum, Mg./100v ml 21.0 14.0 Existent Gum, Mg./l00 ml. (ASTM D 38 11.9 3.2 Oxidation Stability, Min 64 Z 1, 260 Bromine No 71. 7 92. 8 0lefins 49. 0 63. 2 Aromatics 1. 5 8. 8 Knock Rating:

Motor Method, Octane No. 5. 6 81. 5 Research Method, Octane No. 4. 2 91. 5 Tetraethyllead, mlJgal 3.0 Distillation, Gasoline: Over Point, F 94 116 End Point, F" 387 428 10% Evaporation at F 129, 146 50% Evaporation at F 247 246 90% Evaporation at F 350 388 1 2 h e gasoline contained an oxidation inhibiting amount of 2, 6-ditertiary-butyl-kmethylphenol.

In o der to. i l s ra e he mp o e res s obtained with a lubricating oil containing hydrazine, tests were conducted in a two cylinder 90 V-type engine equipped with one /2 in h hevrole powe piston and ne. 3%. in h balance piston which had the crown surface removed and balance established with a ring insert. The power cylinder was fitted with overhead valves. The engine was run at a speed of 2000 r.p.m. with a load of 21 foot pounds for a period of 10 hours. The air-fuel ratio during the test period was 17 to 1 with a spark timing of 23 BTC. The crankcase was charged with 500 grams of oil. Oil was added during the test period as needed. The oil temperature was maintained at 160 F. while the coolant temperature was 90 F. At the end of each test period the engine was disassembled. The deposits were removed and then divided itno those soluble in acetone and those insoluble in acetone. The deposits removed from the then divided into those soluble in acetone and those insoluble in acetone. The deposits removed from the power piston, dummy piston, dummy cylinder wall and dummy cylinder head were weighed, the deposit rating being specified as milligrams of deposit per square inch of surface.

The advantageous anti-varnish properties obtained by incorporating hydrazine in a lubricating oil as compared with the same lubricating oil containing no hydrazine are illustrated by the data set forth in Table 1. Typical physical characteristics of the lubricating oil are as follows:

Lubricating oil Gravity, API 30.6 Viscosity, SUS:

At 100 F 181.0 At 210 F 46.1 Viscosity index 110 Color (ASTM Dl55-45T) 1.75 Pour point, F -l5 Flash point, F 430 Carbon residue, percent 0.04 Neutralization value 0.05

Table 1 Deposit Rating, mg./sq. 1n.

It is apparent from the data tabulated above that a small amount of hydrazine has a very beneficial efiect in reducing the formation of both acetone-soluble and acetone-insoluble deposits on the piston skirts (or in the crankcase area) of the internal combustion engine. In conducting this test the engine was operated with a thermally cracked gasoline.

In order to further illustrate the invention additional tests were made in which hydrazine was replaced with hydrazine salts, i.e., hydrazininm-Z-ethylhexanoate and hydrazinium nonylphenate, and an alkyl substituted hydrazine salt, i.e., dimethyl hydrazinium nonylphenate. The engine was operated on a thermally cracked gasoline when a lubricating oil containing hydrazinium-Z-ethylhexanoate was employed. When an oil containing the other salts was used, the engine was operated with a catalytically cracked gasoline. In making the additional tests, the test procedure was the same as that used in connection with the lubricating oil containing hydrazine except for minor deviations in the engine conditions. For example, in the case of the oil containing hydrazinium nonylphenate and dimethyl hydrazinium nonylphenate the load was reduced to foot pounds while the period of operation was increased to 30 hours. The air- 6 fuel ratio during the test period was 15.5 to 1' with a spark timing of 23 BTC. No oil was added during the test period. The oil temperature was maintained at 160 F. with a coolant temperature of F. The improved antivarnish properties obtained when hydrazinium-Z-ethylhexanoate was added to the lubricating oil are illustrated by the data set forth in Table 2. The hydrazinium-2-ethylhexanoate employed was the product obtained by reacting equi-molar proportions of hydrazine and Z-ethylhexanoic acid at room temperature with stirring for about 15 minutes.

Table 2 Deposit Rating, mg./sq. in.

Lubricating Lubricating Oil 2% Oil Hydrazin- Ium-Z-ethylhexanonte Deposits Soluble in Acetone:

Power Piston 6. 8 0.2 Dummy Piston 8.6 0.2 Dummy Cylinder Head. 04. 1 0. 4 Deposits Insoluble in Aceton Power Piston 0. 8 0.3 Dummy Piston 0. 7 0. 1 Dummy Cylinder Head 22. 4 0.5

The above data show that the addition of hydrazinium- 2-ethylhexanoate to the lubricating oil materially reduces the amount of deposits normally formed in the operation of the engine.

The comparative data obtained when the crankcase of the test engine contained a lubricating oil and the same oil containing 5 percent by weight of hydrazinium nonylphenate are set forth in Table 3. The hydrazinium nonylphenate employed was the product obtained by reacting equi-molar proportions of hydrazine and nonylphenol at room temperature with stirring for about 15 minutes.

lubricating oil and the same oil containing 5 percent by weight of dimethyl hydrazinium nonylphenate are set forth in Table 4. The dimethyl hydrazinium nonylphenate employed was the product obtained by reacting equi-molar proportions of dimethyl hydrazine and nonylphenol at room temperature with stirring for about 15 minutes.

Table 4 Deposit Rating, mgJsq. in.

Lubricating Lubricating Dimethyl Oil hydrazinium nonylphenate Deposits Soluble in Acetone:

Power Piston 1.17 0. 91 Dummy Piston 3. 66 0. 32

The data in Tables 3 and 4 clearly demonstrate the improved anti-varnish characteristics of compositions within the scope of this invention.

While our invention has been described with reference to various specific examples and embodiments it will be understood that the invention is not limited to such examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

We claim:

1. A lubricating composition comprising a major amount of a mineral lubricating oil and about 1 to about percent by weight of a hydrazinium compound selected from the group consisting of hydrazinium phenate, hydrazinium alkyl phenate, a phenol salt and an alkyl phenol salt of an alkyl hydrazine, wherein said alkyl hydrazine contains from one to two alkyl groups and wherein each alkyl group of said alkyl phenate, said alkyl phenol and said alkyl hydrazine contains from 1 to 18 carbon atoms.

2. A lubricating composition comprising a major amount of a mineral lubricating oil and about 1 to about 10 percent by weight of an alkyl phenol salt of an alkyl hydrazine, wherein said alkyl hydrazine contains from one to two alkyl groups and wherein the alkyl groups of said alkyl phenol and said alkyl hydrazine each contains from 1 to 18 carbon atoms.

3. A lubricating composition comprising a major 8 amount of a mineral lubricating oil and about 1 to about- 10 percent by Weight of hydrazinium alkyl phenate, the alkyl substituent containing from 1 to 18 carbon atoms.

4. A lubricating composition comprising a major amount of a mineral lubricating oil and about 1 to about 10 percent by weight of hydrazinium phenate.

5. A lubricating composition comprising a major amount of a mineral lubricating oil and about 1 to about 10 percent by weight of hydrazinium nonylphenate.

6 A lubricating composition comprising a major amount of a mineral lubricating oil and about 1 to about 10 percent by weight of dimethyl hydrazinium nonylphenate.

References Cited in the file of this patent UNITED'STATES PATENTS ,9 ,0 B k AP 9 2,339,797 Musher Jan. 25, 1944 2,544,772 Audrieth et al. Mar. 13, 1951 2,729,690 Oldenburg Ian. 3, 1956 FOREIGN PATENTS 423,938 Great Britain Feb. 11, 1935 OTHER REFERENCES Motor Oils and Engine Lubrication, by Georgi, 1950, Reinhold Pub. Corp, pages and 16.1.

UNITED STATES PATENT oTTTcT VHQERillElQA'llQN @l QGRR'ECTWN Pe-Tene N06 2 966 462 December 2'? 1960 Roderick 5.,- Spindt et al..

It is hereby certified that error appears in the above numbered patent requiring correction and. that the said Letters Patent should read as corrected below.

Column l line 32 for operation read em operating lines 57 and 58 for product read products column 3 line 70 for 'in sufficient to materailly" read is sufficient to materially column l line 12 for paraflnici' read me paTaffini-c line 51 afterherein insert We are celumn 5 line l2 for 'itno" read into lines 13 to 15 strike out The deposits removed from the then divided into those soluble in acetone and those insoluble in acetonea'fl,

Signed and sealed this 23rd day of May 1961,

(SEAL) fittest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents UNITED STATES PATENT orrrct HUN @l? @ECHN Roderick. Sa- Spindt et al0 certified that error appears in the above numbered pat- It is hereby d Letters Patent should read as rent requiring correction and that the sai corrected below.

Column l line 32 for operation' read operating lines 5? and 58 for product read products column 5 line "Z0 for in sufficient to materailly" read me is sufficient to materially column 4 line 12 tor "paraflni'c! read me paraffinic line 51 after "'herein insert we are =3 read into lines 13 to 15 column 5 line l2 for 'itno strike out The deposits removed from the then divided into those soluble in acetone and those insoluble in acetonefla Signed and sealed this 23rd day of May 19610 (SEAL) Attest:

ERNEST W. SWKDER Attesting Officer DAVID L. LADD Commissioner of Patents 

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL LUBRICATING OIL AND ABOUT 1 TO ABOUT 10 PERCENT BY WEIGHT OF A HYDRAZINIUM COMPOUND SELECTED FROM THE GROUP CONSISTING OF HYDRAZINIUM PHENATE, HYDRAZINIUM ALKYL PHENATE, A PHENOL SALT AND AN ALKYL PHENOL SALT OF AN ALKYL HYDRAZINE, WHEREIN SAID ALKYL HYDRAZINE CONTAINS FROM ONE TO TWO ALKYL GROUPS AND WHEREIN EACH ALKYL GROUP OF SAID ALKYL PHENATE, SAID ALKYL PHENOL AND SAID ALKYL HYDRAZINE CONTAINS FROM 1 TO 18 CARBON ATOMS. 